Fred MacMurray is actually an accomplished saxophone player, so he's really playing the saxophone in the party scene.

At the end of the movie, the football filled with flubber gas is seen floating among a series of man-made satellites. They are the same satellites used in Eyes in Outer Space.

In one of the most hapless marketing tie-in attempts in movie history, Hasbro Toys, in cooperation with Disney, issued a toy version of Flubber, marketed just before Christmas time in 1962. Similar to Silly Putty, in that it could bounce like a ball and make comic imprints, the mixture was a combination of rubber, mineral oil, and green food coloring that had been lab-tested with no ill effects and was marketed as being made of "a new parent-approved material that is non-toxic and will not stain." Within weeks, claims came pouring in to both Hasbro and Disney that the toy Flubber was causing full-body rashes and sore throats in many of the children who used it, resulting in several lawsuits by angry parents. Eventually, after much experimentation, and an intensive investigation by the FDA, it was determined that there was a property in the mixture, of unknown origin, that caused an infection of the hair follicles in certain individuals. The product was recalled, but disposing of it turned out to be an even dicier proposition. Trying to incinerate the mixture only produced a heavy, dense black cloud around the Providence, Rhode Island, garbage dump where the attempt was made. Working with the U.S. Coast Guard to sink the substance at sea turned out to be a fiasco, as well, as the next day almost all of the dumped Flubber came floating back into Narragansett Bay. Finally, it was decided to use the mixture as landfill, buried deep under the parking lot at Hasbro's new warehouse, just outside of Providence. Even then, the incredible but true story doesn't end there. A popular "urban legend" among Hasbro employees is that every year, during the hottest days of summer, you can still spot some of the mixture oozing through the cracks in the parking lot.